Question

100 uL of 3-bromopyridine (1.64 g/mL) is dissolved in 10.1mL of DMSO. What is the concentration (in molarity) of the solution that is formed?

Answer 1

Molarity of solution is concentration of solute in moles/liters.

To calculate molarity:

1. Calculate the number of moles of solute present.
2. Calculate the number of liters of solution present.
3. Divide the number of moles of solute by the number of liters of solution.

Given, Volume of 3-bromopyridine = 100 L = 100 10^-3 mL

Density of 3-bromopyridine = 1.64 g/mL

We know, Density = mass / volume

Mass (g) = 1.64 g/mL 100 10^-3 mL = 0.164 g

Number of moles = Wt (in grams) / molecular wt (in g/moles)

= 0.164 / 158 = 1.038 10^-3 moles

Volume of solution = 10.1 mL = 10.1 10^-3 L

Thus, concentration (Molarity) = 1.038 10^-3 / 10.1 10^-3 = 0.1028 M